<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div id="watch-example">
        <p>
            Ask a yes/no question:
            <input v-model="question">
        </p>
        <p>{{ answer }}</p>
    </div>
    <script src="https://cdn.bootcdn.net/ajax/libs/vue/2.7.14/vue.js"></script>
    <script src="https://cdn.bootcdn.net/ajax/libs/axios/1.3.6/axios.min.js"></script>
    <script src="https://cdn.bootcdn.net/ajax/libs/lodash.js/4.17.21/lodash.core.js"></script>
    <script>
        var watchExampleVM = new Vue({
            el: '#watch-example',
            data: {
                question: '',
                answer: 'I cannot give you an answer until you ask a question!'
            },
            watch: {
                // 如果 `question` 发生改变，这个函数就会运行
                question: function (newQuestion, oldQuestion) {
                    this.answer = 'Waiting for you to stop typing...'
                    this.debouncedGetAnswer()
                }
            },
            created: function () {
                // `_.debounce` 是一个通过 Lodash 限制操作频率的函数。
                // 在这个例子中，我们希望限制访问 yesno.wtf/api 的频率
                // AJAX 请求直到用户输入完毕才会发出。想要了解更多关于
                // `_.debounce` 函数 (及其近亲 `_.throttle`) 的知识，
                // 请参考：https://lodash.com/docs#debounce
                this.debouncedGetAnswer = _.debounce(this.getAnswer, 500)
            },
            methods: {
                getAnswer: function () {
                    if (this.question.indexOf('?') === -1) {
                        this.answer = 'Questions usually contain a question mark. ;-)'
                        return
                    }
                    this.answer = 'Thinking...'
                    var vm = this
                    axios.get('https://yesno.wtf/api')
                        .then(function (response) {
                            vm.answer = _.capitalize(response.data.answer)
                        })
                        .catch(function (error) {
                            vm.answer = 'Error! Could not reach the API. ' + error
                        })
                }
            }
        })
    </script>
</body>

</html>